Tool for milling tapered threads with blunt start

ABSTRACT

A tool for cutting tapered threads, said tool being mountable on a tool holder that is in turn positioned onto a spindle of a milling machine controlled by a CNC. The CNC rotates and moves the tool in a pattern to cut a tapered thread on a male connector. The tool includes a step or projection of slightly greater dimension than the threads, and at a position slightly above the threads. During the same operation that the threads are being cut, the tool severs the thin end of the tapered threaded connector to form a blunt end.

BACKGROUND OF THE INVENTION

This invention relates to tools for milling threads for connectors wherein the threaded connecting member may be of tapered design. Many different designs and methods have been used for securing connectors or male tapered thread into a threaded opening or female receptor. One of these tapered designs is the so-called Higbee thread. In many of these connectors there is a problem of providing a tight secure fit between the parts. Further the threaded connector has a tapered or feathered end which upon initial entry to the female counterpart is quite a loose fit which tends to cause a stripping problem: also the tapered end is generally thinner than the other part of the thread and tends to be damaged and to break more readily. Accordingly, one of the solutions to the problem is to form a blunt end on the entering male tapered thread. Another solution such as disclosed in U.S. Pat. No. 4,722,694, the end of the tapered threaded has special hardened surface or piece formed on the end which of course requires addition material and extra production effort. The present invention is directed to providing a milling tool that conveniently forms a tapered thread and in the same operation forms a blunt end for the tapered thread and without requiring reinforcing material.

SUMMARY OF THE INVENTION

A tool mountable on a tool holder that is in turn positioned onto a spindle of a milling machine controlled by a CNC. The tool includes an elongated shank or rod and has milling teeth formed at the free or non-secured end. The CNC control rotates and moves the tool in a pattern to cut a tapered thread on a male connector. The tool includes a cutting shoulder or projection of slightly greater diameter than the threads that is positioned slightly above the threads and, during the same operation that the threads are cut, the thin end of the tapered connector is severed to form a blunt end.

The foregoing features and advantages of the present invention will be apparent from the following more particular description of the invention. The accompanying drawings, listed herein below, are useful in explaining the invention.

DRAWINGS

FIG. 1 is a side view of the thread milling tool of the invention;

FIG. 2 is an end view of the thread milling tool of FIG. 1;

FIG. 3 is a view of the inventive tool mounted on a tool holder for operation; and

FIG. 4 is a view of tapered threaded connector with a blunt end made such as by the inventive tool.

DESCRIPTION OF THE INVENTION

FIG. 1 is a view of a preferred embodiment of the inventive tool 11 for forming tapered threads with a blunt end all within the purview of a single or same operation. Tool 11 comprises an elongated shank or rod 12 having an end 14 that, in operation, is secured in a tool holder 25, as will be described with reference to FIG. 2., hereafter. Cutting teeth 15 are formed on the other or non-secured end 17 of tool 11. An end view of the tool 11 is shown in FIG. 2. The teeth structure 15 includes side rakes 17 formed adjacent the teeth which rake angles or fades onto the periphery of the rod 12. A smooth cylindrical section 19 is formed above the teeth 15. A cutting shoulder or tooth 21 is formed above the smooth section 19; shoulder 21 cuts and blunts the end of the thread formed by the tool 11, as will be discussed further.

FIG. 3 shows the tool 11 mounted in a tool holder 25 which is, in turn, mounted on a spindle 22 of a milling CNC machine. Tool holder 25 includes a drive collar 26 and a threaded locking collar 27, as is known in the art, that enable the tool 11 to be quickly mounted on or removed from the tool holder 25.

As alluded to above, the tool 11 is particularly useful for forming the threads of a tapered screw thread. In many applications including electrical connections utilizing bushings, tapered connectors are employed to assure convenient and fast connections. Also, as indicated in FIG. 4, in a number of automotive applications a tapered connection 28 provides a convenient means of connection in tight or confined spaces. Again as mentioned above a problem arises when using tapered connectors 28 due to the fact that the end of a conventional tapered thread is thin and susceptible to damage and also susceptible to stripping of the threads as the threads are screwed together. This is often due to the fact that there is an initial large spacing between the male and female threads at the entry point that often causes misalignment. Accordingly, one of the ways to minimize or solve the problem is to provide a blunt end 30 for the tapered threads as indicated in FIG. 4. Previously, this required at least one additional step after milling the tapered thread. The present inventive tool provides a tool that mills the tapered threads and in the same CNC operation mills a blunt end on the threads during the same machining procedure or program. As shown in FIG. 1, tool 11 includes a cutting tooth or shoulder 21. In the same CNC operation, the tapered threads are cut and the shoulder 21 is caused to engage and cut the thin end of the threads to provide a blunt end 30 as indicated in FIG. 4. That is, the feathered end of the tapered thread is cut off or blunted. The advantages of a tapered thread are retained while including a stronger blunt end.

While the invention has been particularly shown and described with reference to a particular embodiment thereof it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention. 

1-3. (canceled)
 4. A tool having a cylindrical shank or rod adapted to have one end of said rod mounted onto a milling machine, a) milling teeth formed on the other end of said rod; b) side rakes formed adjacent said teeth which rakes fade or angle into the periphery of said rod to form tapered threads; c) said rod including a cylindrical section above said teeth and in adjacent relation to said teeth; and d) a cutting shoulder formed on said cylindrical section to cut and blunt the end of said tapered thread formed by said tool as the terminal part of the same operation.
 5. A method of forming blunt ends for tapered thread connector consisting of the steps of: a) cutting tapered threads tapering from a first thickness to a feathered or thin end; and b) cutting the thin end of the tapered threads in the same operation as the cutting operation for forming said blunt ends.
 6. A tool for mounting on a milling machine to form tapered threads on a male connector comprising, a) an elongated rod having one end mountable on a tool holder of a CNC machine; b) tapered thread cutting teeth formed at the other end of the rod, said teeth cutting said thread from a first thickness to a feathered or thin end; and c) a cutting shoulder formed on said rod in adjacent relation to said teeth for cutting said thin end of the formed tapered thread during the same operation as the thread cutting operation to provide a blunt end to said tapered thread. 